Method and system for locating end of train units

ABSTRACT

An EOT unit periodically reports its position to an EOT unit tracking station using wireless communication. The location message preferably includes an EOT identifier and a time associated with the position. Optionally, the EOT units are configured to periodically reawaken from a low power state (which may be entered when the EOT units are tipped over while installed on a train or laid on their sides along a wayside or elsewhere) in order to transmit the location message. Optionally, the EOT unit includes a cellular modem and periodically transmits the location message using a cellular network. Optionally, the EOT units are equipped with transceivers and have the ability to receive a query message and transmit a location message in response, and further have the ability to receive a disable message and respond by entering a “no service” state until a special command is entered.

FIELD

The invention relates generally to railroad end of train units, and more particularly to an improved method for keeping track of end of train units.

BACKGROUND

Within the railroad industry, end of train (EOT) units (sometimes also referred to as end of train devices, or ETDs) are typically attached at the rear of the last car on a train. These devices were originally designed to perform some of the functions previously performed by train personnel located in the caboose. Today, EOT units can perform a variety of functions. EOT units monitor air pressure in the air brake pipe and transmit this information to the head of the train (HOT). EOT units also often include an end-of-train marker light. Two-way EOT units can accept a command from the HOT to open the air brake pipe (loss of air pressure in the air brake pipe causes the brakes to activate and stop the train) in an emergency situation. Some EOT units include motion detectors that are used to inform the HOT as to whether, and in some cases in which direction, a train is moving. Other EOT units include GPS receivers that are used to transmit location information pertaining to the end of the train to HOT equipment as discussed in U.S. Pat. No. 6,081,769. EOT units usually communicate with the HOT using radio-based communications.

Supplying power to EOT units is an important consideration. As discussed in U.S. Pat. Nos. 5,267,473 and 6,236,185, it is known to supply power to EOT units using batteries or a combination of batteries and air-powered generators connected to the brake pipe. In order to conserve battery power, EOT units are usually configured to power down when the unit has been in a horizontal orientation for a period of time, such as after being removed from a train by train yard personnel.

Keeping track of EOT units has been a historical problem in the railroad industry. EOT units are expensive and can cost several thousand dollars for a single EOT unit. Because an EOT unit is necessary for each train, railroads are required to buy many EOT units. In addition to being expensive, EOT units are mobile since they are attached to the ends of trains. Unfortunately, this mobility can result in EOT units becoming misplaced. For example, it is often necessary to install and remove EOT units from individual cars in a train yard as consists are reformed. Because the EOT units are often heavy and bulky, yard personnel often simply lay the EOT units by the wayside for collection at a later time. EOT units left by the wayside in this manner often become misplaced or “lost.” Many EOT units are lost this way each year. Even a temporarily misplaced EOT unit can cost a railroad money. For example, rent must be paid for the time when an EOT unit from one railroad is in another railroad's territory. Thus, if another railroad's EOT unit is temporarily misplaced in a railroad's territory, the rent owed to the other railroad is increased as a result.

One solution to this problem is the subject of commonly-owned, co-pending U.S. patent application Ser. No. 10/611,279, filed Apr. 30, 2003, the contents of which are hereby incorporated by reference herein. However, further improvements to the inventions disclosed in that application are possible. What is needed is an apparatus and method for locating EOT units.

SUMMARY

The foregoing needs are met to a great extent by a method and apparatus in which an EOT unit periodically reports its position to an EOT unit tracking station using wireless communication. In some embodiments, the EOT unit includes a cellular modem and periodically transmits a location message using a cellular network. In another aspect, the EOT units are equipped with transceivers and have the ability to receive a query message (i.e., a “ping”) and transmit a location message in response.

In some embodiments, the EOT units are configured to periodically reawaken from a low power state (which may be entered when the EOT units are laid on their sides along a wayside or elsewhere) in order to transmit the location message. After transmitting the location message, the EOT unit will revert to the low power state in order to conserve battery power. Some embodiments may also periodically awaken in order to determine whether any query messages have been directed toward the EOT units. This may be done at a more frequent rate than the transmission of the periodic location message. If no query message is received, the EOT unit reverts to the low power state without sending any message. In other embodiments, the EOT units have the ability to accept a “disable” message and enter a “no service” state until a special message is received. This is done to force the return of the EOT unit to the manufacturer, a repair facility, or some other location, for reactivation in order to provide an added degree of control over the EOT units.

In another aspect, an EOT tracking station is configured to receive the messages from the EOT units and display a location of the EOT units to a user such as an employee of the owner of the EOT units. The EOT location may be displayed textually (e.g., in latitude and longitude coordinates), but is preferably displayed graphically over a map. In highly preferred embodiments, the map display is made available over an interactive website in which users may select individual EOT units for positional display on the map or may select a specific region in which the locations of all EOT units present in the region are displayed. In some embodiments, the user of the website is given the option of initiating a query message and/or a disable message directed toward a particular EOT unit from the website.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant features and advantages thereof will be readily obtained as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIGS. 1 a and 1 b are perspective and front views, respectively, of an EOT unit according to one embodiment of the invention.

FIG. 2 is a block diagram of the EOT unit of FIG. 1.

FIG. 3 is a flow chart illustrating a location reporting subroutine performed by the end of train unit of FIG. 1.

FIG. 4 is a diagram of a first page of a website according to an embodiment of the invention.

FIG. 5 is a diagram of a second page of the website of FIG. 4.

FIG. 6 is a diagram of a third page of the website of FIG. 4.

FIG. 7 is a diagram of a fourth page of the website of FIG. 4.

FIG. 8 is a diagram of a fifth page of the website of FIG. 4

FIG. 9 is a diagram of a sixth page of the website of FIG. 4.

FIG. 10 is a diagram of a seventh page of the website of FIG. 4.

DETAILED DESCRIPTION

The present invention will be discussed with reference to preferred embodiments of end of train units. Specific details, such as types of positioning systems and power supply subsystems, are set forth in order to provide a thorough understanding of the present invention. The preferred embodiments discussed herein should not be understood to limit the invention. Furthermore, for ease of understanding, certain method steps are delineated as separate steps; however, these steps should not be construed as necessarily distinct nor order dependent in their performance.

FIGS. 1 a and b illustrate an embodiment of EOT unit 100. The EOT unit 100 includes a housing 110 in which the internal components of the EOT unit 100 (discussed in further detail below) are located. A handle 111 is attached to the housing 110 to facilitate the installation and removal of the EOT unit 100 from a train car. Also attached to the housing is a connector 120 for connecting the EOT unit 100 to an air brake hose 10 which is in fluid communication with the train's air brake pipe (not shown in FIG. 1 a or 1 b). Also attached to the housing 110 is a coupler 130 which couples the EOT unit 100 to a train car coupling. The EOT unit 100 also includes a marker light 140 attached to the housing 110. Three antennas are also attached to the housing 110: a first antenna 150 for communicating with the HOT, a second antenna 160 for communicating with a cellular base station network, and a third antenna 170 for receiving messages from GPS satellites.

A functional block diagram 200 of the EOT unit 100 of FIG. 1 is illustrated in FIG. 2. The EOT unit 100 is controlled by a processor 210. The processor 210 receives power from a power subsystem 220 which includes an air-powered electrical generator 221 connected to the air brake pipe 10, a rectifier 222, a voltage regulator 223 and one or more batteries 224. Details concerning the power subsystem 224 are discussed in greater detail in corresponding U.S. patent application Ser. No. 10/611,279.

The processor 210 is connected to control an EOT marker light 140 (although a direct connection is illustrated in FIG. 2, those of skill in the art will understand that the processor 210 may supply the control of power to the EOT marker light 140 via a relay or similar device) in accordance with applicable FRA regulations. Also connected to the processor 210 is a tilt sensor 230. The processor 210 uses the tilt sensor 230 to determine when the EOT unit 100 has been placed in a horizontal position so that the processor 210 can take the EOT unit to a low power state to conserve battery power.

Also connected to the processor 210 is an air pressure transducer 240, which is in fluid communication with the air brake pipe 10 and configured to monitor the pressure in the air brake pipe 10. The processor 210 reads the pressure in the air brake pipe 10 and periodically transmits this information to the HOT using the HOT transceiver 250.

An emergency solenoid 280 is also connected to the processor 210 and the air brake pipe 10. When the processor 210 receives an emergency braking command from the HOT via the HOT transceiver 250, the processor 210 controls the solenoid 280 to open, causing a loss of pressure in the air brake pipe 10 and activation of the train's brakes. In some embodiments, another solenoid (not shown in FIG. 2) is also connected to the processor 210 and between the air brake pipe 10 and the air powered generator 221. This solenoid is used to perform certain tests required by the FRA.

The processor 210 is further connected to a positioning system 270, which is a GPS receiver in preferred embodiments but may also be an INS (intertial navigation system), LORAN device, or any other positioning system. The positioning system 270 supplies the processor 210 with reports on the position of the EOT unit 100.

The processor 210 is also connected to a cellular modem 260. The processor 210 uses the cellular modem to send reports including an identifier of the EOT unit 100 and location (and preferably time) information obtained from the positioning system 270 to an EOT tracking station at periodic intervals. The processor 210 also receives “page” messages (messages requesting the EOT unit to report its current location) and “disable” messages (messages instructing the EOT unit to enter an non-operational state) via the cellular modem 260.

During normal operation, the processor 210 controls the EOT marker light 140, communicates air brake pipe pressure information to the HOT, activates the emergency solenoid 280 in response to commands from the HOT, and, in some embodiments performs other functions such as monitoring the status of a motion sensor and transmitting this information to the HOT. These normal operations will not be discussed further herein.

In addition to the normal operations discussed above, the processor 210 periodically transmits location messages. In preferred embodiments, the processor 210 transmits these messages even after the EOT unit has gone into a low power state. As discussed above, the low power state is entered into when the tilt sensor 230 indicates that the EOT unit 100 is in a horizontal position and/or the pressure in the air brake pipe has been lost for some threshold period of time, both of which are indications that the train is not in operation and the EOT unit 100 is not needed. In the low power state, no power is supplied to any component other than a counter circuit (not shown in FIG. 2) which periodically counts down and awakens the processor 210. During the periods when the EOT unit 100 is in a low power state, the processor 210 itself is in a low power state.

Both during normal operations and upon reawakening from the low power state as discussed above, the processor 210 periodically enters a “CALL” subroutine illustrated in FIG. 3 a. The processor 210 determines whether it is time to report its location at step 310. The location messages may be scheduled at a periodic rate such as once per day. Preferably, the processor 210 is programmed to add a small random variation to the scheduled report time (e.g., plus or minus a few minutes) so that messages from all EOT units in operation are not received at one time. If it is not time for the EOT unit 100 to report its position at step 310, the routine ends and the processor 210 puts the EOT unit 100 back into the low power state. If it is time for the EOT unit 100 to report its location, the processor 210 obtains the current location from the positioning system 270 at step 312 and then determines whether the cellular modem 260 has service. If the cellular modem 260 does not have service, the routine ends and the processor 210 puts the EOT unit 100 back into the low power state. If the cellular modem 260 does have service, a message including an identifier of the EOT (typically a number), the current location obtained during step 312, and preferably the time at which the current location was obtained is reported via the cellular modem at step 316. The subroutine then ends and the processor 210 puts the EOT unit 100 back into the low power state.

The EOT unit may also be programmed to respond to a query message (sometimes referred to as a “page”) in some embodiments. In some embodiments, the EOT units are programmed to respond to pages at all times. In other embodiments, the EOT units only check for pages during certain predetermined time periods (e.g., the ten minutes surrounding the top of each hour). Some embodiments will check for pages even while in the low power state while others will only check for pages when in the normal operational state. A flowchart of the “Answer Page” subroutine periodically performed by the processor 210 is illustrated in FIG. 3 b. The processor 210 determines whether a page period such as +/−5 minutes of the top of each hour has been reached at step 320. If the current time is within the page period, the processor 210 obtains the current position from the positioning system 270 at step 322. The processor 210 then determines whether a page (or query) message has been received via the cellular modem 260 at step 324. If a page message has been received, the processor 210 transmits a reply message with the current location and the EOT unit identifier (and optionally the time corresponding to the location information) at step 326. Next, or if no page was received at step 324, the processor 201 again checks whether the current time is within the page period at step 328. If so, steps 324 and following are repeated. Otherwise, the routine ends.

As discussed above, some embodiments of the EOT unit 100 are also responsive to a disable message. The processing for such a message is similar to the processing of FIG. 3 b, except that the processor 210 enters a “no service” state in which it ceases to perform normal operations until a special command is received.

Those of skill in the art will recognize that various modifications to the EOT unit 100 are possible. For example, it is possible to operate the EOT unit 100 solely with battery power rather than using batteries in conjunction with an air powered generator. Cellular modem 260 may be replaced with any type of wireless communication system. Various other modifications to the components of the EOT unit 100 are also possible.

The EOT unit 100 may communicate with any of a number of tracking stations via any of a number of methods. In preferred embodiments of the invention, the EOT unit 100 communicates with a centralized EOT tracking station that maintains a database of information pertaining to the EOT units and that is accessible to users via the Internet. There may be separate EOT tracking stations for individual railroads, or there may be a centralized EOT tracking station that monitors all EOT units. Such a centralized tracking station may restrict the EOT information that various users are able to view. In some embodiments, a user from a particular organization (e.g., a railroad) may only be allowed to view information pertaining to EOT units owned by that organization. In other embodiments, a user from an organization may be allowed to view information pertaining to EOT units that they own and EOT units owned by others that are within territory in which they own the tracks. The latter ability allows a railroad to quickly locate and return EOT units in their territory for which they are paying rent.

FIG. 4 illustrates an opening web page 400 of an internet-based web tracking station according to an embodiment of the invention. A map 401 of a large portion of North America is displayed in the center window 410. A map width text box 411 allows the user to control the width of the map 410. To the left of the map window 410 are a Query window 420 and a Results window 440. The query window includes an EOT text box 422 in which the user may enter one or more identifiers for EOT devices in which the user is interested. Once the user has entered the identifiers of the EOT devices in the text box 422, the user presses the Search button 432. In response, a map 402 centered on the location of EOT device entered into the text box 422 (in this case, EOT device 77950) is displayed in the window 410 as illustrated in FIG. 5. The map 402 is preferably a richly featured map that shows railroad tracks 510 and roads 511 as well as geographical features and political boundaries (not shown in FIG. 5). In this example, it appears that EOT device 77950 is positioned on a railroad track, which is a good indication that it is in service and mounted on a train.

The Results window 440 displays the EOT identifier along with a last contact date and time (i.e., the date and time when the EOT device last reported its position). The Results window 440 also includes a Ping checkbox 441 and a History checkbox 442. When the Ping checkbox 441 is selected and the Ping button 436 is pressed by the user, a ping (query) message will be sent to the corresponding EOT unit (in embodiments in which the EOT units only respond to pages during certain time periods, the ping message will be delayed until the next period). Similarly, when the History checkbox is selected and the History button is pressed, a history of dates and times of prior location messages from the corresponding EOT unit will be displayed.

In addition to searching by EOT numbers, it is also possible to perform an area search using the “Near City/State” window 424. As shown in FIG. 6, when a city (e.g., Chicago) is entered in the City textbox 425, a state (e.g., Illinois) is entered into the State textbox 425, and a desired search radius (e.g., 20 miles) is entered into the Radius textbox 426 and the Search button 432 is pressed, a map 403 of the Chicago area showing the location of all EOT devices in the Chicago area is displayed in the map window 410. The Results window 440 lists contact information for all of the EOT units shown on the map 403.

The user may also focus on a particular EOT unit using the zoom icon 405. For example, unlike most of the EOT units shown in the map 403, EOT unit 77990 appears to be located away from any railroad tracks. After clicking on the zoom icon 405, the user may draw a box around EOT unit 77990. This will result in the display of a map 403 on a smaller scan with EOT unit 77990 at the center as shown in FIG. 7. At the smaller scale, it is clear that the EOT unit 77990 is indeed located away from any railroad track. Given the presence of stub-in 511 a, it is possible that EOT unit 77990 has been removed from a train that was once “parked” on the stub-in 511 a and was left behind and is now lost. Alternatively, the EOT unit 77990 may be in an equipment shed located near stub-in 511 a. In this case, the tracks 511 are owned by a first railroad but the EOT unit 77990 is owned by a second railroad. This means that the first railroad is paying rent to the second railroad for the use of EOT unit 77990. Therefore, if EOT unit 77990 is indeed lost and/or sitting in an equipment shed, the first railroad is losing money by letting the EOT unit 77990 sit around. A user may avoid this loss by locating the EOT unit 77990 through the website and directing appropriate personnel to return EOT unit 77990 to the first railroad.

In addition to the functions described above, the website also provides a Search All button 430 that, when pressed, will result in the display of all EOT units. A download button 438 will download textual information from selected EOT units to a file specified by the user. When the user presses the History button 436, an EOT History window 810 appears. The user can then enter the particular EOT units for which a history is desired in the EOT textbox 820 and a period of time for which the history is desired in the Age textbox 830. When the History button 840 is pressed, a map 910 showing the locations, dates and times of all messages received from the desired EOT units is displayed to the user as shown in FIG. 9. When the user presses the Ping button 436 (and no Ping checkbox has been checked in the Results window), a Ping window 1000 appears as shown in FIG. 10. The user may enter an EOT identifier in the EO textbox 1010 and a desired email address in the email textbox 1020. When the desired information is entered, the user presses the Ping button 1030 and a query message is sent to the EOT unit 100.

While the invention has been described with respect to certain specific embodiments, it will be appreciated that many modifications and changes may be made by those skilled in the art without departing from the spirit of the invention. It is intended therefore, by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention. 

1. An end of train unit suitable for use on a train, the end of train unit comprising: a processor; an end of train marker light connected to be turned on and off under the control of the processor; a first wireless transceiver connected to the processor; a second wireless transceiver connected to the processor, the second wireless transceiver being configured to communicate with a device located at a head of the train; and a positioning system connected to the processor; wherein the processor is configured to periodically perform the steps of obtaining a location of the end of train unit from the positioning system; and sending a message via the first wireless transceiver to a device located off of the train, the message comprising an identifier associated with the end of train unit and location information pertaining to the end of train unit.
 2. The end of train unit of claim 1, wherein the message further comprises a time corresponding to the location information.
 3. The end of train unit of claim 1, wherein the processor is further configured to enter a low power state upon detecting a condition indicating that it is not necessary for the end of train unit to continue normal operation, and wherein the processor is further configured to perform the obtaining and sending steps during the condition.
 4. The end of train unit of claim 3, further comprising a tilt sensor connected to the processor, wherein the condition is an indication from the tilt sensor that the end of train unit is not in a vertical orientation.
 5. The end of train unit of claim 3, further comprising a pressure transducer connected to the processor, the pressure transducer being configured to measure an air pressure in an air brake pipe of the train, wherein the condition is an indication from the pressure transducer that an air pressure in the air brake pipe is below a threshold.
 6. The end of train unit of claim 1, further comprising an air powered generator connected to supply at least some power to the processor, the air powered generator being configured to generate electrical power when in fluid communication with a pressurized air supply from an air brake pipe of the train.
 7. The end of train unit of claim 1, wherein the processor is further configured to receive a query message and transmit a message including the identifier and a location of the end of train unit in response.
 8. The end of train unit of claim 1, wherein the processor is further configured to receive a disable message and suspend normal operations until an enable command is received.
 9. The end of train unit of claim 1, wherein the first wireless transceiver comprises a cellular modem.
 10. A method for displaying a location of at least one end of train unit to the user comprising the steps of: receiving a message from the end of train unit, the message comprising a location of the end of train unit and an identifier of the end of train unit; storing the location and the identifier; receiving a query from a user; and displaying the location and the identifier to the user in response to the query.
 11. The method of claim 10, further comprising the steps of accepting a designation of an end of train unit identifier and a ping command from a user and transmitting a query message including the identifier in response to the ping command.
 12. The method of claim 10, further comprising the steps of accepting a designation of an end of train unit identifier and a disable command from a user and transmitting a disable message including the identifier in response to the disable command.
 13. A method for operating an end of train unit on a train comprising the steps of: periodically obtaining a location of the end of train unit from a positioning system; and periodically transmitting a message via a wireless transceiver to a device located off of the train, the message including the location and an identifier of the end of train unit.
 14. The method of claim 13, further comprising the steps of: detecting a condition indicating that normal operation of the end of train unit is not necessary; and entering a low power state upon detection of the condition; wherein the periodically obtaining and periodically transmitting steps are performed both during normal operation and during periods in which the condition is detected.
 15. The method of claim 13, further comprising the steps of: receiving a query message; and transmitting a message including a position of the end of train unit and an identifier of the end of train unit in response to the query message.
 16. The method of claim 13, further comprising the steps of: receiving a disable message; and halting normal operations in response to the disable message. 